England and Exeter flanker Tom Johnson has revealed that he faces up to three months out of action after suffering a serious knee injury at the weekend.

Johnson was stretchered off in the 16th minute of the match between Exeter and Leinster and he has now confirmed the serious nature of his injury. Scans have revealed the back-rower has suffered a grade three medial collateral ligament tear which is set to keep him out of action for the next three months, including the forthcoming Six Nations.

He last played for England during the autumn internationals but has been a regular feature of Stuart Lancaster's side since he took over the England head coach post. He was included in the latest revamped elite player squad and would have hoped to play some part in the Six Nations.

And while three months is a huge portion of Johnson's season, he revealed that it could have been worse. "The way it was, the way the Leinster player fell on me, it could have been nine months out, so it's much better than it could have been," Johnson told the Western Morning News. "It's pretty much fully ruptured. There's a little bit of the ligament still hanging on but I think, all in all, I'll take that.

"I was thinking it was a long-term injury when it happened. At least this means I'll hopefully be back before the end of the season. It can be a week either way, depending on the rehab, but there are many things that could happen on the way back.

"As a very rough estimate, you tend to say ten or 12 weeks, but there's no real way of knowing. I'm just thanking my lucky stars that it's not going to be as long as I thought. Then, hopefully, I can kick on when I get back fit again."

The news of Johnson's injury follows hot on the heels of Calum Clark's setback who was ruled out of the Six Nations with a shoulder injury on Tuesday. Loose-head prop Alex Corbisiero will miss England's first two fixtures, against Scotland and Ireland, after undergoing a procedure on Wednesday to clean out his troublesome knee.

And England will also be without Freddie Burns for at least the Scotland game on February 2, with the Gloucester fly-half expected to be out for two to three weeks with knee ligament damage.

"Alex Corbisiero's knee hasn't settled down," Lancaster explained. "It keeps swelling after small amounts of exercise. There is a loose body in there. He has gone in for a scope today to get that loose body taken out and hopefully that will settle down for him. We will get him rehabbed and back playing for London Irish. That will take him out of the first two games as a minimum.

"Freddie Burns has had a scan on his MCL. It is a grade two injury so not as bad as first feared but it will keep him out for two or three weeks. We will try to get him back as soon as we can."

Lancaster added that it was "too early to tell" whether Manu Tuilagi will have recovered from an ankle injury in time for the tournament opener at Twickenham. In more positive injury news, full-back Alex Goode has overcome a shoulder problem and will play for Saracens against Cardiff Blues in the Anglo-Welsh Cup this weekend.